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-   -   Evaporation (http://www.cfd-online.com/Forums/fluent/39737-evaporation.html)

Shanti February 20, 2006 20:07

Evaporation
 
Hi

I am modelling a two-phase system. One of the phases has 2 species. One of the species is evaporating into the other phase(ie air). I have included mixture model and species transport model. Does this take into consideration, that the liquid phase is being converted into a gaseous phase, or do i need to define a UDF for it?

Please help me..

Thanks

turbomachinery February 21, 2006 00:08

Re: Evaporation
 
yes, there is a tuturial case in FLUENT about water boiling and there is a UDF using in simulating this question.

MANOJKUMAR February 21, 2006 04:40

Re: Evaporation
 
Hi, I setting the injection in my problem but there is not evaporated it say incompleted. what tempereture to given for the evaporation.

James February 21, 2006 14:10

Re: Evaporation
 
Hi,

what is your boiling point temp. and what about your partial vapor pressure? This is very important and it is good to have it set to piecewise polynomial. It affects to a great extent the evaporation process and also the boiling point temp. should be very accurate.

Any idea what your operating pressure is? The boiling point temp. also varies with the operating pressure.

If you are not having any evaporation, then i suggest as a first step to check these properties.

Also, what boundary conditions did you use for the droplets at the walls? Maybe most of your droplets are hitting the wall and so this boundary condition is important. The trap condition is the most ideal. With this, when a droplet hits a wall, it is trap and it completely evaporates and the liquid fuel evaporated is added to the gaseous phase. Fluent doesn't take the energy needed for this process from the flow and so your enthalpy balance is not affected.

James


MANOJKUMAR February 22, 2006 05:52

Re: Evaporation
 
THANKS JAMES CAN U GIVE UR E-MAIL ID MY E-AMIL IS ms_project05@rediffmail.com

ilphma July 12, 2014 04:59

i'm using fluent for simulating an injection. because of the hot airstream, the droplets reach the boiling point very fast and there is no chance for most of them to evaporate with law2. but when they reach to boiling point, as said in user guide, they just stay in boiling point and in this case there is no new evaporating!

how can i fix that problem? how they can continue evaporating after reaching the boiling point temperature?


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